ESA uses cookies to track visits to our website only, no personal information is collected. By continuing to use the site you are agreeing to our use of cookies. OKFind out more about our cookie policy.

Image of the Week

Hipparcos interactive data access tool

A powerful new tool: screenshot taken from the Hipparcos interactive data access tool showing the astrometric residuals of Hipparcos star HIP 4463 as a function of the epoch of the transit observations.

A new, stand-alone Java tool, the Hipparcos interactive data access tool, has been released allowing users to interrogate data of ESA's first astrometry satellite, Hipparcos. The tool allows displaying data ranging from overall statistics and distributions of user-defined samples of stars down to solution details of individual stars. It also provides access to sets of ground-based photometric and spectroscopic data, for instance allowing users to construct Hertzsprung-Russell diagrams. The tool contains the 1997 and 2007 Hipparcos data sets. Spacecraft and focal-plane calibration data are also available.

As an example of the power of the tool, the above image shows the astrometric residuals of Hipparcos star HIP 4463 (the spectroscopic binary ƞ And) as a function of the epoch of the transit observations. The 1σ error bar of each residual as used in the astrometric solution is shown. The interpretation of these residuals as function of time is non-trivial since they refer to different scan directions. The distribution of epochs of observation over the mission is very much a function of ecliptic latitude. Clusters of observations are seen when the local scan direction is close to perpendicular to the direction from the observation to the direction of the Sun on the sky. This also corresponds with a small to zero parallax factor for these observations. The tool easily allows to re-arrange the plot and show the residuals as function of, for instance, parallax factor or parallax direction.